Heart of Darkness

The story written by Joseph Conrad who is British. Its background was that African worked under Europe as a colony. The thing was connected the story that the main character named Charlie Marlow went to Africa. He felt how there was and met many slaves there. One day, he heard about the man named Kurz who was a really good worker. Marlow  started to be interested in him, then he went to see him.
The story was very defficult to understand. I was confused who was speaking each scene so I am not sure the end of the story. I said its background and the story connected but I wasn't able to understand for sure.